Interestingly, I have just had my first nose around to see what the GTS MC shifts are doing, and was pleasantly surprised.
A same year car with slightly higher mileage (12k, mine has 9k) are still just above £60k.
There are some higher mileage examples around at late £50k's but little or nothing has moved.
The GS are still occupying the £25-35k band, so the GT 4.2 is being held up above £40k by the GS, and thus the GTS is intern being held up by the GT 4.2 way above £50k
Suppose its only been 4 or 5 months since I have had her, but still, very pleased with the residuals.